Rotary internal combustion engines use the rotation of a piston to convert pressure into a rotating motion. In these engines, the rotor typically includes a number of seals that remain in contact with a wall of the rotor cavity of the engine throughout the rotational motion of the rotor to create a plurality of rotating chambers when the rotor rotates. One well-known type, the Wankel engine, has a generally triangular rotor received in a two-lobed epitrochoid cavity. Other rotary engines types exist as well.
Some internal combustion engines, including some rotary engines, include a pilot subchamber for pilot ignition. However, known arrangements are not optimized, in terms of combustion arrangements and characteristics, and thus room for improvement exists.